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Manifold Pressure

B

Brother23

Messages
184
Country
germany
Hi folks,

currenlty I try to bring in realistic performance tables for my airplane.

At sea level its easy to adjust. But for a clean performance curve, there

is the problem.

The aircraft has a turboloader. But when I add manifold pressure maximum

and minimum, the plane is even to fast or to slow at other altitudes.

So i see, that I didnt understand the system behind the manifold pressure

settings in the aircraft.cfg.

At what means the compression ratio there?

Thanks and Greetings
Brother23
 
Until now I was only interested in flight dynamics and how it influences handling characteristics of an airplane in flight. So I do not understand much
about modelling an engine in MS Flight Simulator. Nontheless I´m interested to learn more about modelling engines in FSX. Perhaps we can work out a solution together.

I clearly can tell you , what a compression ratio is in real-life:

The compression ratio of an piston engine is the ratio between the volume in a cylinder when the piston is at bottom dead center and the volume of the cylinder when the piston is at top dead center. It is one of the factors which determines the performance of an engine. A higher compression ratio results in more energy that an engine can yield in burning fuel.

I assume in FSX compression_ratio as well determines the performance of a piston engine (among other values in the .cfg-file, as cylinder_displacement, number_of_cylinders etc.) .

In FS2004 the value max_rated_hp seemed not to influence the engine performance when I remeber my tests well. Rather it set the volume or pitch of sound in external view .

My first tests with the Money in FSX also showed no increase in max. speed when the value is increased from 270 HP to 900 HP.

But when I add manifold pressure maximumand minimum, the plane is even to fast or to slow at other altitudes
Click to expand...

Did you take into account the value critical_altitude in the .cfg-file ? The critical altitude is defined as the altitude at which the turbocharged engine will develop the sea level maximum manifold pressure rating at full throttle.

In Microsoft´s words: critical_altitude= altitude to which the turbocharger will provide the maximum design manifold pressure .



What real-life engine data do you have available ?

Which aircraft are you designing ?

Carl
 
Thx

I managed to setup the turboloader correctly. But I had to triple the

max effective height of the loader from the real number to FSX that it

calculated correctly.

That plane is a 30s-era racing plane.

Greetings
 
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